Disposable containers are used in many industries to hold and dispense fluids of various natures. When the fluid has been used and the container is empty, or when it is filled with waste, it is usually thrown away. Some examples of this type of packaging are flexible plastic i.v., catheter and irrigation bags commonly used in hospitals.
Sterile i.v. bags are normally used to dispense plasma, whole blood, replacement electrolyte, etc. The bags are usually imprinted or screen-labelled with the required documentation to identify the contents. When using containers of the i.v. bag type, the normal procedure is to dispense a metered amount over a given period of time by unmonitored, gravity-fed, drip feeding. The containers themselves come in different sizes, and i.v. fluids are administered to patients requiring widely varying flow rates. For example, 250 milliliter (ml.) to 3 liter plastic i.v. bags or bottles may be used to dispense a solution of 0.9% saline, Ringers lactate, 5% glucose, plasma, or blood to an adult over a 10-40 minute or longer time period, at rates of 1-25 ml. per minute (or more depending on the need).
It is a common practice to pre-set the gravity-driven flow rates via a visual drop-counting metering mechanism located above the i.v. catheter. However, pre-set flow rates can vary over a substantial range, due to changing resistance to outflow resulting from several variables. Some of the variables that can affect the flow rate include: the changing height of the insertion site relative to the fluid level as the patient moves about; a partial or complete closing (kinking) of the tubing; the thrombosis (clotting) promoting propensities of the solution being dispensed; the angle of the needle influencing the occlusion of its beveled opening; the settling of the various components of the fluid in the container, such as blood cells; and other reasons. In a chaotic environment such as an operating or emergency room, it is not always possible for someone to constantly monitor the amount of fluid in an i.v. bag.
It is detrimental to a patient to have the flow of an i.v. fluid come to a complete stop. Complications which can occur after the flow has stopped include the clogging of the needle due to blood clotting, usually requiring reinsertion of a new needle, or blood passing out of the patient into the tubing. It is important to note that, in addition to pain, the risk of infection and hematoma increases every time a needle has to be inserted and reinserted into a vein. In a high stress environment such as a hospital operating room or trauma center, staffs are often engaged in a variety of vital tasks at one time and the fluid levels of i.v. bags are often not changed, resulting in harm to the patient.
This contributes to the rise in healthcare costs, as patients require more care; while physicians and medical facilities are forced to payout large sums of money in medical malpractice lawsuits.
Similarly, many endoscopic surgeries, require that the bodily cavity be irrigated with a saline or similar solution. These irrigation solutions are delivered through a container, similar to an i.v. bag. Failure to monitor the bag may result in injury to the patient; for example, failure to maintain irrigation pressure, during a bladder surgery may result in a collapse of the compartment, causing the surgeon to lose track of the area he was working on or even cause inadvertent injury to the urethral orifices or puncturing the bladder cavity.
Operating room nurses and technicians currently have the responsibility for monitoring i.v. fluid levels and making sure they do not run out. However, in a busy operating room environment there are many distractions and demands for attention increasing the likelihood of an i.v. fluid inadvertently running out. A need, therefore, exists to find a practical, low-cost solution to the problem of how to determine, without constant direct human observation, when the fluid in one of these containers reaches a level requiring action by the nurse, doctor, attendant, or patient, and to get their attention at the required time. The present invention fills this need.